Comparing Sassafras and White Ash for Epoxy River Tables
Choosing between domestic hardwoods for an epoxy river table or wide tabletop requires balancing mechanical performance against dimensional stability. Sassafras and White ash offer distinctly different physical profiles. Data published by the USDA Forest Products Laboratory in the Wood Handbook (FPL-GTR-282) provides direct benchmarks to help evaluate how each species behaves in wood-and-epoxy designs.
Weight and Density
Specific gravity serves as the primary indicator of density and tabletop heft. At 12% moisture content, Sassafras has a specific gravity of 0.46, while White ash measures 0.60. For large river tables where deep epoxy pours already add substantial deadweight, Sassafras provides a noticeably lighter tabletop. White ash yields a heavier, denser top that gives a substantial feel but requires sturdier base assemblies and consideration during transport.
Dent Resistance and Surface Hardness
Surface toughness determines how well a tabletop resists dings from daily dining or office use. At 12% moisture content, White ash provides a side hardness of 1,320 lbf and a compression perpendicular to grain value of 1,160 lbf/in². Sassafras has an unlisted side hardness in the handbook, but its compression perpendicular to grain at 12% moisture content is 850 lbf/in². White ash offers significantly higher resistance to localized surface crushing and perimeter denting, making it well-suited for high-traffic surfaces. Sassafras remains adequate for residential furniture, though it is softer under direct impact.
Stiffness, Strength, and Overhangs
Table designs featuring long unsupported spans or cantilevered ends demand high bending strength (modulus of rupture, or MOR) and stiffness (modulus of elasticity, or MOE):
- Modulus of Rupture (12% MC): Sassafras reaches 9,000 lbf/in², compared to 15,400 lbf/in² for White ash.
- Modulus of Elasticity (12% MC): Sassafras rates at 1.12 million lbf/in², while White ash reaches 1.74 million lbf/in².
White ash is much stiffer and stronger under bending loads. For wide epoxy voids or expansive dining tables built without center stretchers, White ash slab edges provide greater structural support along the resin interface.
Seasonal Movement and Shrinkage
Differential movement between curing epoxy and natural timber is a major consideration in tabletop fabrication. Because cured resin is relatively inert, lower wood movement reduces stress along the bondline.
From green to ovendry conditions, Sassafras exhibits radial shrinkage of 4.0%, tangential shrinkage of 6.2%, and volumetric shrinkage of 10.3%. In comparison, White ash shrinks 4.9% radially, 7.8% tangentially, and 13.3% volumetrically. Dimensional change coefficients reflect this difference: per 1% change in moisture content below the fiber saturation point, Sassafras expands or contracts by 0.00137 radially and 0.00216 tangentially. White ash moves more, with coefficients of 0.00169 radially and 0.00274 tangentially.
Both timbers share an identical tangential-to-radial (T/R) shrinkage ratio of 1.6, meaning both species dry with uniform proportions and minimal tendency toward severe distortion. However, the lower total volumetric shrinkage and smaller movement coefficients of Sassafras make it more dimensionally stable once sealed into a table.
Moisture Content and Heartwood Decay Resistance
In green stock, the Wood Handbook records White ash moisture content at 46% for heartwood and 44% for sapwood (green moisture values for Sassafras are not listed). For both timbers, slabs must be thoroughly dried and acclimated before pouring epoxy; always consult the resin maker’s data sheet for surface preparation instructions.
Regarding natural durability, Sassafras heartwood is rated as Resistant to decay, while White ash is rated as Slightly or nonresistant. While indoor tabletops are rarely exposed to outdoor rot, Sassafras provides extra peace of mind in high-humidity or semi-protected environments.
Figures from the USDA Wood Handbook (FPL-GTR-282), Tables 4-1, 4-3, 5-3b, 13-5 and 14-1. Clear, straight-grained specimens; real slabs vary.
| Property | Sassafras | White ash |
|---|---|---|
| Specific gravity (12% MC) | 0.46 | 0.60 |
| Side hardness, lbf (12% MC) | — | 1,320 |
| Modulus of rupture, lbf/in² (12% MC) | 9,000 | 15,400 |
| Modulus of elasticity, million lbf/in² (12% MC) | 1.12 | 1.74 |
| Compression perpendicular to grain, lbf/in² (12% MC) | 850 | 1,160 |
| Radial shrinkage, green to ovendry (%) | 4.0 | 4.9 |
| Tangential shrinkage, green to ovendry (%) | 6.2 | 7.8 |
| Volumetric shrinkage, green to ovendry (%) | 10.3 | 13.3 |
| Dimensional change coefficient, tangential (per 1% MC) | 0.00216 | 0.00274 |
| Dimensional change coefficient, radial (per 1% MC) | 0.00137 | 0.00169 |
| Green MC of heartwood (%) | — | 46 |
| Tangential/radial shrinkage ratio (calculated) | 1.6 | 1.6 |
| Heartwood decay resistance (Table 14-1) | Resistant | Slightly or nonresistant |
Which to Pick When
Neither species is universally superior; each fits specific structural and aesthetic needs:
- Choose Sassafras when building large tabletops where overall weight is a concern, or where maximum dimensional stability is desired to limit stress on the epoxy seam. Its natural rot resistance also suits environments with varying ambient humidity.
- Choose White ash for heavy-use dining tables, desks, and designs with long unsupported spans or substantial overhangs. Its superior stiffness (1.74 million lbf/in² MOE) and higher side hardness (1,320 lbf) resist bending and everyday surface dents far better.
Sources
Published October 28, 2026. Sources are linked in the text.
Header image: original graphic by BigEpoxy.com.
Staff note: When preparing joinery or anchoring mechanical fasteners into the underside of a slab, note that the shear strength parallel to the grain at 12% moisture content is 1,240 lbf/in² for Sassafras versus 1,910 lbf/in² for White ash, giving ash a clear advantage in holding threaded inserts and resists tear-out under heavy mechanical loads. (Source: USDA Forest Products Laboratory, Wood Handbook (FPL-GTR-282, 2021).)